1. Field
The invention is in the field of apparatus and methods for automatically sorting items and for removing those items which do not conform to predetermined standards. It is specifically concerned with the automatic sorting of elongate items, particularly food items, such as elongate strip potato pieces cut from peeled, raw, white potatoes in the production of commercially prepared food products, such as french fries, to eliminate those of such items as are defective.
2. State of the Art
There are numerous machines described in the patent literature for sorting such items as fruits and vegetables. Many of these machines use light sources to illuminate the items to be sorted. In some cases the translucence of an item is a measure of its condition, defective items exhibiting different translucence than sound items. In such cases, light sensors are arranged to detect the light transmitted by the items being sorted. In other cases, the amount of light reflected from an item is a measure of its condition. In the latter cases, sensors are arranged to detect reflected light. In still other cases, the color of an item indicates its condition. In such other cases, reflected light of a certain wavelength is detected by light sensors, and associated filters are provided to pass to the sensors only reflected light of that wavelength.
In U.S. Application Ser. No. 895,256, filed Apr. 10, 1978 by two of the present inventors, Norman Brent Wassmer and Joseph L. Hodges, entitled "Differential Reflectivity Method and Apparatus for Sorting Indiscriminately Mixed Items", now U.S. Pat. No. 4,186,836, issued Feb. 5, 1980, there is disclosed a system for automatically sorting items of the nature of cubed, raw, white potatoes by passing such items, first, through a viewing area and, then, through a removal area as a continuous heterogeneous bed substantially no thicker than the thickness of the individual items. The potato cubes are indiscriminately mixed and the bed has considerable width relative to the width of the individual items.
An endless belt conveyor carries the bed through the viewing area, where it is flooded with radiant energy (made up of visible light energy and infrared energy) from light fixtures which extend along the width of the viewing area and produce an integrated spread of the radiant energy throughout the viewing area.
The indiscriminately mixed cubes making up the bed reflect the component radiant energies of mutually different wavelengths in respectively different degrees, depending upon condition of the individual cubes. The potato cubes reflect such energies according to a predetermined relationship if there are no dark spots attributable to defects of various kinds. If there are such dark spots, the energies will be reflected in other than the predetermined relationship.
The respective energies reflected from the bed passing through the viewing area are individually sensed by pairs of sensing devices, e.g. pairs of diodes of a dual diode array scanning camera, which is focused on respective, contiguous, sub-areas of the viewing area extending transversely of the bed. Signals from the sensing devices of each pair are compared, e.g. by comparison circuitry of the scanning camera. Data signals result if the comparison of sensed signals show that the predetermined relationship between reflected energies exists for particular sub-areas of the viewing area. These control the operation of removal devices in the removal area.
The removal devices are suction tubes arranged across the width of the removal area. They have respective widths corresponding in widths and locations with predetermined pluralities of the sub-areas of the viewing area, so that any width portion of the bed passing through the removal area for which a predetermined number of data signals are produced will be removed.
The removal devices are individually operated by respective pneumatically actuated, power piston and cylinder assemblies controlled by data signal processing means, such as sophisticated electronic circuitry and data processing components.
U.S. Pat. No. 3,675,769, issued July 11, 1972, discloses a sorting system that detects ratios of reflected light of two wavelength ranges in order to differentiate between field-dug potatoes and rocks and dirt clods as the potatoes are being harvested. With this system, as with the aforementioned color sorting systems which detect light within restricted wavelength ranges, the individual items to be sorted are arranged in side by side rows, along which they are passed single file and are viewed individually as they pass.
However, there is nothing in the prior art which suggests how cut potato strips or similar slender elongate items should be handled to achieve sorting results similar in effectiveness to the results achieved by the aforesaid U.S. Application Ser. No. 895,256.